Organic electro-luminescent display (OLED) has been widely used in the fields of display, illumination and others, due to its self-illumination, low operating voltage, light weight, flexibility, and high color saturation etc. The preparation process of the organic electro-luminescent device includes: forming a thin-film transistor (TFT) on the substrate, and forming an anode, a pixel defining layer, a light-emitting layer and a cathode in sequence on the thin-film transistor, in which the anode and the thin-film transistor are electrically connected to the drain electrode.
However, since a portion of the light emitted from the light-emitting layer is incident on the active layer of the thin-film transistor through the refraction and reflection of the film layer in the organic electro-luminescent device, the portion of the light affects the characteristics of the thin-film transistor. This causes an instability of the threshold voltage (Vth) of the thin-film transistor and an increase in off-state current (Ioff), thereby affecting the light-emitting effect. In particular, in low temperature poly-silicon (LTPS) thin-film transistors, since low temperature poly-silicon is very sensitive to light, the light emitted from the light-emitting layer is incident on the low temperature poly-silicon layer, which will generate photoelectrons, thereby significantly affecting the characteristics of the thin-film transistor.